An antenna device in which a plurality of split ring resonators (SRRs) are electrically connected using a conductive via-hole is known. In this antenna device, as a method for lowering a resonant frequency without increasing an area, there is a case where a width of a void provided at the SRR is decreased. However, there are limitations to decrease of the width of the void for manufacturing reasons. Therefore, it is impossible to lower the resonant frequency to equal to or less than a certain frequency, and there are limitations to size reduction of the antenna device.